A Lectin-Binding Assay for the Rapid Characterization of the Glycosylation of Purified Glycoproteins
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Most proteins have carbohydrate chains (glycosylation) attached covalently to various sites on their polypeptide backbone. These posttranslational modifications, which are carried out by cytoplasmic enzymes, confer subtle changes on the structure and behavior of a molecule, and their composition is very sensitive to many environmental influences (1, 2, 3). There is increasing interest in determining the glycosylation of a molecule because of the importance of glycosylation in affecting its reactivity (1,4,5). This is particularly true in the production of therapeutic glycoproteins by recombinant methods, where glycosylation can be determined by the type of host cell used or the production process employed (2). Glycosylation is also important in disease situations where changes in carbohydrate structure could be involved in the pathological processes (3). Unfortunately, the glycosylation of proteins is very complex; there are variations in the sites of glycosylation, the types of amino acid—carbohydrate bond, the composition of the chains, and the particular carbohydrate sequences and linkages in each chain (3,4). In addition, within any population of molecules, there is considerable heterogeneity in the carbohydrate structures (glycoforms) that are synthesized at any one time (1). This is typified by some molecules showing increased branching, reduced chain length, and further addition of single carbohydrate moieties to the internal chain.
KeywordsCarbohydrate Structure Sialic Acid Content Sambucus Nigra Agglutinin Lens Culinaris Agglutinin Maackia Amurensis Agglutinin
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